Vertebral Endplate Cavities with Titanium Cages in Posterior Lumbar Interbody Fusion.

Background:  Vertebral endplate cavities (VECs) have been reported with the use of titanium (Ti) cages. Only few articles have recently demonstrated unfavorable radiographic changes in the form of cysts or cavities, which may predispose to nonunion.

Methods:  The aim was to assess the prevalence of VEC in posterior lumbar interbody fusion (PLIF) using Ti cages and to estimate their impact on fusion. The term "cavity" was used to describe the endplate changes. Computed tomography (CT) analysis of the VECs and fusion status following PLIFs with Ti cages was conducted by two observers. VECs were assessed according to the size, multiplicity, location, and presence of sclerosis.

Results:  Forty-two consecutive patients with surgeries conducted on 52 levels were enrolled. There were 20 males and 22 females. The mean age was 43.6 ± 10.89 years. The mean follow-up was 20.85 ± 8.49 months. Definite union was seen in 48 levels (92.3%) by observer 1 and in 40 levels (76.9%) by observer 2. The strength of agreement was moderate. The presence of VEC was observed in 9 levels (17.3%) by observer 1 and in 12 levels (23.1%) by observer 2. The strength of agreement was moderate. The majority of VECs in the endplates were less than 5 mm. The strength of agreement was high. The strength of agreement for location and multiplicity were moderate. The VEC was significantly correlated with the fusion status.

Conclusions:  Our study confirmed that VECs were observed following Ti cage placement after PLIF procedures. They tend to be small and might be associated with nonunion. Furthermore, it reflected the limited inter-rater reliability of the assessment of both the fusion status and VEC morphology after Ti PLIF cage placement.